Rotary system mounted piezoelectric generator, self-powered wireless communication terminal and wireless communication system

1. A rotary system mounted piezoelectric generator comprising: a beam in which a whole or part thereof is formed of a piezoelectric material and whose one end is provided in a rotation system; and a weight which is attached to the other end of the beam, wherein the beam is formed by a folded structure in which the beam is extended from an installation point of the rotation system to the weight toward a direction of a rotation center of the rotation system such that when the rotation system is rotated, a centrifugal force applied to the weight is modulated by a second force other than the centrifugal force, a degree of freedom of motion of the weight when seen from the rotation system is two or more-dimensional and the beam is constantly deformed so as to correspond to a variation in a sum of a vector of the centrifugal force which is changed according to a number of revolutions of the rotation system and which is applied to the weight and a vector of the second force which does not depend on the number of revolutions of the rotation system such that a rotation center of the weight is moved according to the number of revolutions of the rotation system with the degree of freedom which is two or more-dimensional and that a locus of the weight can be changed.

2. The rotary system mounted piezoelectric generator according to claim 1 , wherein when the rotation system is rotated, the motion locus of the weight is displaced by the second force from a true circle in which the rotation center of the rotation system is a center point and is changed in a shape of an ellipse or a dynamic closed loop according to the number of revolutions of the rotation system such that the centrifugal force acting on the weight is modulated.

3. The rotary system mounted piezoelectric generator according to claim 1 , wherein the second force is gravity which is exerted on the weight.

4. A rotary system mounted piezoelectric generator comprising: a beam in which a whole or part thereof is formed of a piezoelectric material and whose one end is provided in a rotation system; and a weight which is attached to the other end of the beam, wherein when the rotation system is rotated, and the beam is formed in a shape of an arc having a diameter on a line connecting an installation point of the rotation system and a rotation center of the rotation system such that a motion locus of the weight is displaced from a true circle in which the rotation center of the rotation system is a center point, a length of the arc of the beam when seen from the installation point of the rotation system falls within a range from 120° to 240 °.

5. The rotary system mounted piezoelectric generator according to claim 1 , wherein the beam has a spiral structure and is arranged on a plane perpendicular to a rotation shaft of the rotation system.

6. The rotary system mounted piezoelectric generator according to claim 1 , wherein the one end of the beam is inclined and is fixed to the rotation system by a movable spring structure such that the degree of freedom of motion of the weight is improved and that a vibration mode is increased.

7. The rotary system mounted piezoelectric generator according to claim 1 , wherein the weight includes a magnet or a ferromagnetic material, the second force is formed by a magnetic force and the centrifugal force acting on the weight is modulated by a variation in the magnetic force exerted on the weight.

8. The rotary system mounted piezoelectric generator according to claim 1 , wherein the weight includes a fluid resistor, the second force is formed by a fluid resistance force and the centrifugal force acting on the weight is modulated by a variation in the fluid resistance force exerted on the weight.

9. A self-powered wireless communication terminal comprising: a wireless communication means which transmits digital data from an AD converter; and the rotary system mounted piezoelectric generator according to claim 1 , wherein alternating-current power obtained by the rotary system mounted piezoelectric generator is rectified and stored, is stabilized in voltage by being stepped down or stepped up and is used as a power supply voltage for the AD converter and the wireless communication means.

10. The self-powered wireless communication terminal according to claim 9 , comprising: a piezoelectric sensor which is connected to the AD converter such that a sensor output is input to the AD converter; a capacitive AC coupling which is connected between the AD converter and the piezoelectric sensor; and a capacitor and a resistor which are connected in parallel to an output of the piezoelectric sensor so as to adjust sensitivity of the output of the piezoelectric sensor and a low frequency response cutoff frequency, wherein a resistor voltage division direct-current voltage of the power supply voltage is added to an output voltage of the piezoelectric sensor which is AC coupled such that the output voltage of the piezoelectric sensor is offset by a direct-current voltage and is input to the AD converter.

11. The self-powered wireless communication terminal according to claim 9 , wherein the wireless communication means uses a subcarrier multilevel phase-shift keying (MPSK) modulation scattering communication system to perform wireless communication.

12. A wireless communication system comprising: the self-powered wireless communication terminal according to claim 9 ; and one or more readers, wherein the reader utilizes maximization of a reception signal amplitude of the reader with timing at which polarized waves of an antenna of the self-powered wireless communication terminal and an antenna of the reader coincide with each other or with timing of a shortest distance so as to estimate an instantaneous rotation angle of the rotation system, to evaluate a correlation function of the rotation angle of the rotation system with respect to data received from the self-powered wireless communication terminal, to perform rotational coordinate transformation so as to transform the received data by the rotation angle of the rotation system into a stationary coordinate system and to monitor a number of revolutions of the rotation system.

13. The wireless communication system according to claim 12 , wherein two or more of the readers are provided, and the readers use different inquire carrier signal frequencies so as to avoid radio interference and can simultaneously and continuously read transmission information from one or more of the self-powered wireless communication terminals.

14. The wireless communication system according to claim 12 , wherein two or more of the self-powered wireless communication terminals are provided, the self-powered wireless communication terminals have different response subcarrier signal frequencies and the readers utilize the response subcarrier signal frequencies of the self-powered wireless communication terminals so as to avoid radio interference and can simultaneously and continuously read the transmission information from the self-powered wireless communication terminals.

15. The wireless communication system according to claim 12 , comprising: an analysis means, wherein two or more of the self-powered wireless communication terminals are provided, and the analysis means identifies, based on a mutual correlation function C n,m (τ) =∫X n (t —τ) X m (t) dt of observation waveform data X 1 (t), X 2 (t), . . . (here, t is an elapsed time) which is observed in each of the self-powered wireless communication terminals and which is received by the reader, a magnitude and a positional relationship of an event which causes the observation waveform data.

16. The wireless communication system according to claim 12 , comprising: an analysis means, wherein the rotation system has a specific convex-concave pattern in a surface which makes contact with another structure, and the analysis means obtains, based on an autocorrelation function of observation waveform data which is observed in each of the self-powered wireless communication terminals and which is received by the reader or a mutual correlation function of the specific convex-concave pattern and the observation waveform data, rotation period information on the rotation system, information on a section in which the rotation system makes contact with the another structure and information on a height of the specific convex-concave pattern.